Gears or Converter for 60'ft gains.

Discussion in 'Got gears?' started by Buickboy69, May 15, 2018.

  1. Buickboy69

    Buickboy69 Active Member

    So was wondering which would give you a better 60'ft, a converter or rear end gear change to me it seems like the converter would be the logical choice but changing rear end gears is a bit more old school and still seems to work as well.
    I mean ideally you would do both, but if you where a high school kid ballin on a budget what would you do?
     
  2. mltdwn12

    mltdwn12 Platinum Level Contributor

    I'd think it's a combination of convertor and suspension. I say that because in the 90's I ran 4.56's, 11" convertor, no-hop bars, Moroso front springs and 90/10 front shocks. Car ran low 12's and would 60' at ~1.65 or so. When I rebuilt everything about 10 years ago I went with a JW 10" convertor, 3.55 gears and added a rear roll bar kit (the name escapes me right now, one of the popular setups) anyway after dialing in launch rpm, I got the car down to 1.58 60' times. The only downside seemed to be a bit of slip on the top end. When I put the car on a chassis dyno, as soon as the run was finished the operator asked what kind of convertor I had because it didn't seem to be hooking up on the top end. Engine dyno showed 503 HP, chassis dyno said 365. It ran a best of 11.77 but only at 112 mph.
     
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  3. Buickboy69

    Buickboy69 Active Member

    I tend to agree with that. I would think that you would gain more from the extra launch rpm than the gear reduction in a set of numerically high gears.
     
  4. rkammer

    rkammer '71 GS455 Arctic White

    When it comes to just 60 ft times, definitely the converter change will help e.t. the most. The rear gear change has more to do with e.t. after the launch and matching RPM and tire size with the engine's power band.
     
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  5. Buickboy69

    Buickboy69 Active Member

    How much difference do yall think gears and a larger tire is actually worth in 60' and et
     
  6. rkammer

    rkammer '71 GS455 Arctic White

    Well, I'll start by saying that your 1.65 short times aren't bad. But, your 500 HP car should run a little better than 112 MPH I should think. Perhaps 114-115. But, if you can improve your short time by say, 0.2 seconds, your e.t. should improve from 11.77 to something around 11.50. If you can get the MPH up several MPH, with a little less slip in the converter, you could see 11.30s or better. What size and type tire are you running now?
     
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  7. mltdwn12

    mltdwn12 Platinum Level Contributor

    rkrammer, not trying to hijack Buickboys thread, but my best 60' time was a 1.58 with the 11.77 run. I run a 9" MT slick, 29" tall. The extra stall did help getting off the line cleanly, especially running a 950 double pumper. I actually found the best launch was to bring the car just off idle to about 900 rpm and hammer it from there. Power braking didn't cut any time.
     
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  8. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    It would be easier to answer the question if we knew what gears you had now and what you were intending to switch to. Same for the converter. Some info on the rest of the car would help too.
     
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  9. Buickboy69

    Buickboy69 Active Member

    Probably gonna to be going from 3.08s to 3.73 and from a 2000stall to a 2800 or 3000
     
  10. rkammer

    rkammer '71 GS455 Arctic White

    What size tire are you running now and what size will you change to? I still think with a 28 in. tire and your 3.73s and 2800+ stall you will go below 11.50.
     
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  11. Buickboy69

    Buickboy69 Active Member

    235/60r15 Hoosier double line is what I plan to run, been running a the old style Mickey Thompson et street ss the same size but it's quite a bit harder than the Hoosier
     
  12. hugger

    hugger Well-Known Member

    235/60 is way to small for any consistency, you need to step up to a 275/60 on a 8.5 or 10in wheel

    One of my previous combos went 1.54 with the above, with a 3800 stall and a 3.31 gear with bone stock suspension, car trapped 114 to 116 at 3950lb

    Unless you plan to drive around on the drag radials, go with the MT Pro's
     
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